Electrical coil



A.W. FISHER AND G. S. SNAVELY'.

ELECTRICAL COIL. APPUCATION FILED JAN. 29, 1919.

' Patented July 6, 1920.

INVENTORS I t E WMLL y.

To all whom it may concern:

UNITED "STATES PATENT'OFFICE.

ARTHUR W. FISHER, OF WILKINSBURG, AND CLARENCE S. SNAVELY, OF PITTS- BURGH, PENNSYLVANIA, ASSIGNORS TO THE UNION SWITCH 8a SIGNAL COM- PANY, 0F SWISSVALE, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA.

ELECTRICAL corn Specification of Letters Patent.

Patented July 6, 1920.

, Be it known that we, ARTHUR W. FISHER and CLARENCE S. SNAVELY, citizens of the United States, residing at WVilkinsburg and Pittsburgh, respectively, in the county of Allegheny and State of Pennsylvania,have invented certain new and useful Improvements in Electrical Coils, of which the following is a specification.

Our invention relates to coils of wire for taken on the line II -III in Fig. 2. Fig. 4

1s a fragmental sectional view of the coil shown in the preceding views, taken on the same section line as 3, and showing the coil in uncompleted condition, this view being on a larger scale than Fig. 2 to illustrate moreclearly the method of constructing the coil. Fig. 5 is a View showing a flexible washer used in the construction of the coil shown in the preceding views.

Similar reference characters refer to similar parts in each of the several views.

Referring first to Fig. 3, the coil is wound on a tube 1, usually of hard fiber, having no flanges at its ends. Before the winding process is started, a washer 2 is attached to each end of the tube, each of which washers is of flexible material, such as unbleached muslin or other similar fabric, and each of which is preferably circular in form, as shown in Fig. 5. The diameter of each washer is considerably greater than the diameter of the finished coil, for a reason which will appear hereinafter. Eachwasher is provided at its center with radially disposed slits 2 of sufficient length to allow the tube 1 to pass through the washer.

One of these washers is placed on each end of the tube with the triangular projecnovel features thereof in claims.

tions 2*, due to the slits, pointing inwardly as shown in Fig. 4, and the washer is then firmly attached to the tube by twine or like material 3 wound around these projections. Each washer then flares outwardly from one end of the tube, as illustrated in Fig. 4:. The tube is then placed in awinding machine and the first layer of wire is wound thereon, whereupon the machine is stopped and the insulation is scraped from several turns of the wire. A flexible lead 5 is then soldered to the bared wires, and the lead is attached to the tube by twine 7 or similar material. completed in the usual manner, a fine cotton The winding of the coil is then thread being cross woven between each two layers of wire to hold the wire in place and bind the coil together.

A few extra turns of this thread are wound at each end of the wire part ofthe coil to form a cotton pad or wall 8 at each end of the coil. This wind ing process, consisting of the interweaving of a cotton. thread throughout the coil as a binder. and the formation of the cotton heads or walls, is not original with us, but, on. the other hand, may be applied by winding machines which are now in commercial use. When the winding has been completed,

another flexible lead 10 is soldered to a few turns of wire in the outermost layer.

During the winding of the coil, a number of loops of twine 6 are preferably inserted between layers of wire, and these loops are used later to tie the flexible leads tightly against the cotton wall as shown in Fig. 2. By this means the leads are securely held in place for the subsequent application of the cotton washer, and will withstand the strains incident to the handling and carrying the coil by the leads.

After the winding of the coil has been completed, each washer 2 is drawn tightly back over the corresponding end of the coil and bound firmly to the cylindrical surface of the coil by twine 9 or like material. Of course, suitable holes or slits are made in one of the washers to permit the leads 5 and 10 to project from the finished coil. Pressure may be applied to the ends of the coil, if desired, to force the leads into the cotton wall 8 so that the length of the coil .will not exceed the traverse of the winding twine 9.

as construction is concerned, and is ready to be impregnated with an insulating .compound or given any other finishing treatment that may be considered desirable.

The size of each washer 2 is preferably such as to permit it to be drawn back about one half the length of the coil, as shown in vFig. 3, although it is only necessary that the washer should extend back far enough to permit it to be secured to the coil by the The construction of coils by the method thus described has ,many advantages over the usual spool construction involving the use of solid'heads on the tube 1. The

- cost of the material for such heads, and the cost of making the same, are greater than: the cost of the cotton washer employed our invention. The application of the solid heads in the spool construction requires a separate operation, as well as special tools, whereas in the practice of our invention, the fabric washer is applied by the winding machine operator, and is part of the coil winding operation. Only one operation,

viz., the setting up of the tube in the,wind-.

, ing machine, is required for the complete winding, securing of leads and application of cotton washers and of the twine 9.

The usual spool construction has sometimes beeneliminated by the use of a tape covering,but this scheme requires the removal of the coil from the winding machine, and the weaving of the tape through the center of the coil; this process consumes 'considerably more material, and requires more labor, than the fabric washer method embodying our invention.

Another important advantage of the con.- struction embodying our invention, is the elimination of dead space in the coil. In spool wound coils,.a certain amount of dead space exists due to the heads, or in a space i required for housing flexible leads, or in both places. All this dead space is eliminated in coils constructed in accordance I with ourinvention, the leads being pressed into the cotton wall, if necessary, .so as not to increase the normal length of the coil.

In'the case of tape covered coils referred to above, the necessity for running the tape through the center of the coil, requires that the coil be made with an inside diameter length, to maintain the same shunting characteristics, and will at the same time, cause the magnet to have greater power.

The elimination of the space required for the spool heads in spool'construction, enables the length of iron in the magnetic structure to be reduced, so as to approximate the length of the winding. This feature increases the energization for a given length of iron, hence gives a greater density of magnetization and for this reason permits a reduction in the size of pole faces or an increase in core pin lengths to obtain the same shunting characteristics. This feature also causes the magnet to' have greater power.

It can thus be seen that considerable waste space is eliminated by the construction of the coil'in accordance with our invention, and that this elimination makes possiblethe design of a more efficient magnet than has been possible heretofore.

Although we have herein shown and described only one method of coil construction embodying our invention, it is under- .stood that various changes and modifica- 'tions may be made therein within the scope of-the appended claims without departing from the spirit and scope of our-invention. Having thus described our invention, what we claim 1s:

1. The method of constructing a wire coil on a flangeless tube, which consists in attaching two flexible washers to the tube one at each end, winding the wire on the tube, and subse uently wrapping each washer over the a jacent end and cylindrical surface of the coil and attaching it to the cylindrical surface of the coil.

2. The method of constructing a coil of wire on a flangeless. tube, which consists in slitting two flexible washers radially at the center so that the tube will pass through them, placing said washers on the tube one at each end with the projections due to said slits pointing inwardly, attaching such projections to the tube, winding the wire on the tube, and subsequently wrapping each washer over the adjacent end and cylindrical surface of the coil and securing it to the cylindrical surface of the coil. I

3. The method of constructing a coil of wire on a flangeless tube, which consists in attaching two flexible washers to the tube, I

one at each end, winding one layer of wire on the tube, removing the insulation from several turns of said layer at one end and soldering a flexible lead to said turns, winding the balance of the wire on the tube, removing the insulation from several turns at the end of the last layer of wire and soldering a flexible lead to said turns, and

subsequently wrapping each ,washer over the adjacent end of the coil and attaching it to the cylindrical surface of the coil, said flexible leads being brought out through .a suitable hole in the adjacent washer near the outer rim of the coil.

4. The method of constructing a coil of wire on a fiangeless tube, which consists in attaching two one at each end, winding the wire .on the tube with a few turnsof insulating string at each end of each layer, and subsequently 10 wrapping each washer over theadjacent end flexible washers t0 the tube.

and cylindrical surface of the coil and binding it to the cylindrical surface. I

In testimony whereof we aflix our signatures in presence of two witnesses.

ARTHUR W. FISHER. CLARENCE S. SNAVELY.

Witnesses:

A. HERMAN WEG/NER, R. M. GILsoN. 

